OS is not booting, asking for BIOS update

My Dell inspiron n5050 laptop, i tried to change the OS from windows 7 sp1 to windows 7, after installtion, it is unable to restart. when i choose startup repair, it showing problem with BIOS that it is not ACPI compliant. Please contact ur system vendor for an updated BIOS.

technical info: STOP: 0X000000A5 (......)

Initially N5050A03 was installed. Later I updated it to A04. Now In Dell website, it is showing only A03 and A05 as supported BIOS for my Laptop. Now what to do to update the BIOS without OS

If you boot the recovery DVD with a thumbdrive attached you should be able to execute the command line bios update against the system bios. That A04 is not available from Dell any longer only means that Dell feels that there was an issue with that version that was sufficiently buggy to pull it from the site. You should be using your Service Code to look up the BIOS to use though and not the model because some BTO (Build To Order) laptops can be different.